[dba-Tech] dhcp stuff

JWColby jwcolby at colbyconsulting.com
Sat Dec 16 14:46:26 CST 2006


I am trying to get my router (DL-624) to be the DHCP server (which it has
always been) and to assign static addresses to my various computers.  I have
discovered the mac addresses, built up the list of statically assigned mac /
ip address sets etc.  One of my machines has two 1gb NICs.  For come reason,
one of those NICs ends up being assigned a Dynamic address even though the
router has a mac / ip pair in the static assignment table and it is enabled.
I have double checked everything.
 
The NIC that windows claims is the second port is the culprit.  If I go into
the properties inside of windows and specifically tell it to use a given
address (statically assigned inside of Windows) it does take that address,
but if I tell it to dynamically acquire an address it gets the dynamic
address that the router assigns.
 
The router, at this instant, has TWO IP addresses for this NIC - a
statically assigned (now matching both in the router table and in Windows)
and a dynamically assigned address by the router.  If I try (for example) to
remote desktop into the dynamically assigned address the attempt fails,
which makes sense because the actual port (mac address) is statically
assigned (in windows and the router) to a different address.
 
I am wondering why the router dynamically assigns an address to that MAC
even though there is an entry in the static address table for that MAC, and
in fact I have told Windows to statically assign an address to that NIC to
match that static address assigned by the router.
 
In essence, I can now remote desktop in (from inside of my network) to
either nic on that machine, at the "statically assigned" ip addresses, and
cannot remote desktop to the "dynamically assigned" ip address for the
offending mac, so I know now which addresses are valid.  But why the dynamic
assignment which is in fact not used by the machine?
 
I sure wish I understood this stuff better.
 
John W. Colby
Colby Consulting
www.ColbyConsulting.com
 



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